The straddle checkerboard was an important part of many Cold War ciphers. Can a reader decipher three ciphertexts I created with this encryption method?

A picture of Arnold Schwarzenegger, taken at the set of “Conan the Barbarian”, shows an encrypted (?) text. Can a reader decipher it?

In the early 1970s, cryptographers in the USA and in East Germany developed two suprisingly similar encryption methods. Did one party steal from the other? Or was a useful concept invented twice?

The Science Museum in London is hosting an exhibition about secrets and ciphers. The exhibits include a quilt bearing encrypted messages.

Today I’m going to present a 28 letter message that has been encrypted with a Playfair cipher. To my knowledge, such a short Playfair cryptogram has never been solved before.

Codebreaking expert and book author Helen Fouché Gaines created a crypto challenge that is unsolved to this day.

Magnus Ekhall from Sweden has solved my Playfair challenge from April 2019. With only 30 letters, this ciphertext is the shortest of its kind ever broken.

A US radio station and a US non-profit organisation have received letters that look like code messages. Can a reader decipher them?